Emerging extended-spectrum beta-lactamases in Proteus mirabilis

Area of Science:

• Microbiology
• Infectious Diseases
• Antimicrobial Resistance

Background:

• Proteus mirabilis is a common cause of healthcare-associated infections.
• Beta-lactamase enzymes confer resistance to beta-lactam antibiotics, a critical class of antimicrobials.
• Extended-spectrum beta-lactamases (ESBLs) represent a significant challenge in treating bacterial infections due to their broad activity.

Purpose of the Study:

• To investigate the prevalence and types of beta-lactamase production in Proteus mirabilis isolates.
• To identify specific ESBLs, including extended-spectrum beta-lactamases (ESBLs), in clinical isolates.
• To analyze the clonal diversity and potential dissemination patterns of ESBL-producing Proteus mirabilis.

Main Methods:

• Antimicrobial susceptibility testing was performed on 282 Proteus mirabilis isolates.
• Beta-lactamase production was phenotypically screened.
• Isolates positive for beta-lactamase production were further characterized for ESBL production.
• Specific ESBLs (PER-1 and TEM-52) were identified.

Main Results:

• Beta-lactamase production was detected in 52% (147/282) of the Proteus mirabilis isolates.
• Of the beta-lactamase producers, 48% (70/147) were identified as producing ESBLs.
• The identified ESBLs were PER-1 (52 isolates) and TEM-52 (18 isolates), with PER-1 being reported for the first time in this species.
• Analysis suggested different clonal spreading patterns for the PER-1 and TEM-52 ESBL determinants.

Conclusions:

• A significant proportion of Proteus mirabilis isolates in this northern Italian hospital produce beta-lactamases, including clinically relevant ESBLs.
• The emergence of PER-1 in Proteus mirabilis highlights the evolving landscape of antimicrobial resistance.
• Understanding the epidemiology and dissemination of ESBL-producing Proteus mirabilis is crucial for infection control and treatment strategies.